Method of treating tin-bearing tungsten ores



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METHQiD 01E TREATING: TIN-BEARING TUNGSTEN ORES.

No Drawing. Application filed May 26,

' To altwhom it may concern Be it known that T, FREDERICK M. BnoKnT,

a cltlzen of the United States, residing at Niagara Falls, in the county of Niagara and 5 State of New York,'have invented certain new and useful Improvements in Methods of Treating Tin-Bearing Tungsten Ores, of which the following is a specification.

This invention is a method for the treatment of tin-bearing tungsten ores, and is applicable for the' preparation from such ores of tungsten metal or ferrotungsten commercially free from tin. The method is particularly applicable to the treatment of such ores as Chinese wolframite, which often contains sufficient tin to render it practically worthless for many smelting operations, in the course of which tin is readily reduced. While such ores may vary considerably in composition, the following may be regarded as typical: 7

Per cent.

wo, e9- 71 'FeOLni 13- 15 MnO 9- 11 Sn I 0.4-0.7

complete elimination of the tin may be secured by subjecting the properly ground ore to a roasting operation within suitable temperature limits, and thereafterdissolving out the tungsten content by a suitable alkaline reagent, which is preferably caustic soda. The tungsten may be precipitated from the resulting substantially tin-free sodium tungstate solution in the form of its calcium salt, which is then smelted in known -manner for the preparation of metallic tungsten or its alloys with iron or other metals.

Following is a specific example of my method, it being understood that the invention is not restricted to the specific operating conditions therein described:

A tin-bearing tungsten ore of the type mentioned above is rather finely ground, preferably to 40 mesh and finer; and the fine ore is then subjected to an oxidizing roast, preferably ata temperature range of about 1920. Serial no. 384,266.

460-720" "C. Temperatures somewhat below this range, say down to 300 (3., may be employed with somewhat inferior results; but materially higher temperatures, say 900 C. or upward, render the tungsten content of the ore substantially insoluble and are there-- fore to be avoided.

The roasted ore is then treated with a hot caustic soda solution until substantially all of its tungsten content is dissolved. A 20% solution maintained just short of its boiling temperature is satisfactory for this purpose. Tf necessary the residues from the first operation may be re-treated with fresh alkali. i

The residue from this treatment should contain substantially the whole of the tin content of the ore, together with practically all of its manganese and iron content, and may be discarded so far as the purposes of the present invention are concerned. The tungsten content of the solution is precipitated, preferably as the calcium salt, and the latter is subjected to electric furnace reduction, preferably using silicon or other noncarbonaceous reducing agent in case a lowcarbon product is desired.

I claim 1. Method of treating tin-bearing tungsten ores of the wolframite type, comprising roasting a suitably comminuted ore, and extracting the tungsten content thereof by an alkaline solvent, whereby a substantially tin- FREDERICK M. BECKET. 

